Question

I’m using knitr 0.5 for my analysis and it throws this warning

Warning in parse_params(params) :
  (*) NOTE: I saw options " label = TrtScores-SD-Response, echo = FALSE, results = asis"
 are you using the old Sweave syntax? go http://yihui.name/knitr/options

for this chunck

<< label = TrtScores-SD-Response, echo = FALSE, results = asis >>=
R code
@

and knitr 0.5 becomes very slow. Any idea to overcome this warning. Thanks

Answer 1

You just need to add quotes around the results argument, like this:

<< label = TrtScores-SD-Response, echo = FALSE, results = "asis" >>=
R code
@

As documented at http://yihui.name/knitr/options (the web page to which the error message thoughtfully directed you):

All option values, except the chunk label, must be valid R expressions just like how we write function arguments. For example, options that take character values must be quoted as you do in R (e.g. should write fig.path=”abc” instead of fig.path=abc, and out.width=’\textwidth’ instead of out.width=\textwidth)

And then later on the same page:

results: (‘markup’; character) takes three possible values

See also the “Transition from Sweave to knitr” page, which addresses this and other differences between Sweave and knitr. Like all of Yihui’s documentation, it’s excellently put together.